The present invention relates generally to isokinetic or speed-regulated exercise apparatus, and more particularly to improvements in devices wherein the exercise resistance is provided via electrical generation and absorption means.
A simple and effective exerciser utilizing variable resistance means comprising an electrical generator and means for loading the output of the generator is described in my U.S. Pat. No. 4,082,267. Others have also used generators for similar purposes. However, such direct-current generators utilized in exercising equipment can develop certain problems, and the present invention is directed to improvements which will eliminate these problems.
In the standard construction of such a generator, a permanent magnetic field surrounds a rotating wound armature. To carry the current generated in the windings of the armature out of the generator, a system of brushes and commutator, or, minimally, brushes and slip rings is required. These components are subject to contamination and wear in use, and must be expensively constructed for long-term service under heavy use in an exerciser.
Also, in the standard generator construction, as the current-carrying windings are part of the rotating armature, the capacity of the generator is severely limited by the lack of an efficient thermal pathway to dissipate heat generated in these windings. Disproportionately large and expensive generators of this type are therefore required to provide the exercise resistance in exercisers for the larger and stronger muscle groups of the body. Alternatively, auxiliary cooling devices, such as fans, must be incorporated to carry away the excess heat generated by the device.
A partial solution to these difficulties in the construction of an inexpensive electromagnetically regulated exerciser was suggested in U.S. Pat. No. 3,984,666 to Barron. In that patent, an automotive type alternator was utilized as the exercise resistance producing means. In the standard construction of such an alternator, the current carrying windings are located in the stator or external stationary shell of the device, allowing efficient dissipation of the heat generated therein, either directly into the surrounding ambient, or to a heat sink. However, extensive external electronic circuitry is required to control the windings of the rotor, and external power must be applied thereto to generate the required magnetic field. While the major currents of the stator windings may be carried directly out of the device, brushes and slip rings are still utilized to power the windings of the rotor. It may be seen that while the utilization of a conventional alternator instead of a conventional D.C. generator in an exercise device to produce the exercise resistance may improve the thermal characteristics of the system, it substantially complicates the associated controller circuitry required, and increases the overall manufacturing cost of the apparatus.
It is therefore a primary object of the present invention to improve upon prior devices in the provision of an electromagnetically regulated exerciser wherein a variable exercise resistance is provided by an electrical generator having high thermal dissipation capacity and direct electrical connections to the current carrying windings, while requiring minimum associated control circuitry and no external excitation power.